The majority of domestic dishwashers currently in use have an adding device for holding one or more cleaning agents which are added to the washing liquid during the course of a washing cycle for the purpose of cleaning the washable items that have been placed in the dishwasher. The cleaning agent which has been preloaded into the adding device is usually fully released into the washing compartment during the washing cycle and mixed with the washing liquid that is circulated there. In terms of size, the adding device is dimensioned such that it can be filled with exactly the amount of cleaning agent that is required for one washing cycle. The dishwasher user is therefore obliged to fill the adding device with the amount of cleaning agent required for the cleaning cycle at the start of each washing cycle. This operation is inconvenient for the user of the dishwasher. Moreover, in the case of such dishwashers, the problem arises that the amount of cleaning agent loaded into the adding device can vary from user to user, and also from washing operation to washing operation. An incorrectly dosed amount of cleaning agent can lead to unsatisfactory washing results if the cleaning-agent dose is too small on one hand, and can result in a waste of cleaning agent and hence an adverse effect on the environment if a dosed amount of cleaning agent is too large on the other hand.
Furthermore, adding devices which add the amount of cleaning agent stored therein to the washing liquid all at once do not allow more complex washing programs to be performed. For example, in certain situations it might be suitable to add the cleaning agent to the washing liquid at different instants. Adding devices which are designed for holding a single cleaning-agent dose cannot support complex washing cycles of this type.